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  • Journal article
    Tse KK, Chung HSH, Hui SYR, 1999,

    Stepwise quadratic state-space modeling technique for simulation of power electronics circuits

    , IEEE Transactions on Industrial Electronics, Vol: 46, Pages: 91-99, ISSN: 0278-0046

    - A fast and accurate technique for simulation of power electronics circuits is presented. The methodology begins by using Chebyshev polynomials to derive an adaptive stepwise quadratic state-space model for each piecewise-linear circuit topology. The state-space equation sets are integrated with modified nodal equations. The key feature of this algorithm is that it gives an approximate value of the optimum simulation step size for analysis of each circuit topology in order to achieve a desired accuracy in calculating the state transition matrix of the topology. Moreover the algorithm hybridizes the advantages of calculating the circuit responses at circuit level and determining switching instants at device level. The switching instants are calculated directly by solving simple quadratic equations. Furthermore it is unnecessary to have prior knowledge of the circuit operations such as the topology sequence and duration. The algorithm automatically looks for a valid topology at any time instant. The proposed method is illustrated with the examples of a practical induction heater and a boost dc/dc regulator. The theoretical predictions are verified with the results obtained in experiment and available literature. © 1999 IEEE.
  • Journal article
    Tse KK, Chung HSH, Hui SY, 1999,

    Quadratic state-space modeling technique for analysis and simulation of power electronic converters

    , IEEE Transactions on Power Electronics, Vol: 14, Pages: 1086-1100, ISSN: 0885-8993

    This paper presents a quadratic state-space modeling technique for analysis of power electronic converters. The methodology is based on using a least-square-error fitting to derive a quadratic state-space representation for each topology, together with automatic determination of switching topology. The algorithm integrates the advantages of calculating topology responses at the circuit level and determining switching instants at the device level. Several key features of the new model that lead to significant improvements in computational efficiency include: 1) its simple quadratic polynomial representation for the state-transition matrix in solving the differential equations describing each topology; 2) its direct and single-step calculation of the switching instants; and 3) its generality in determining valid topology without a prior understanding of the switching relationships. Several examples illustrating the generality and simulation speed of the proposed approach are presented. The computational efficiency of the new approach is demonstrated by comparing its simulation time with commercial software using the stepwise integration algorithm. The accuracy is verified with the exact method and available literature.
  • Journal article
    Lu Z, Qian Z, Green TC, 1999,

    Predicted control scheme of shunt active power filter with artificial neural network

    , Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering, Vol: 19, Pages: 22-26, ISSN: 0258-8013

    A predicted control scheme of shunt active power filter with artificial neural network has been presented, which is suitable to the motor driver with frequent speed/torque changes. Based on the artificial neural network, the active power filter can work properly to cancel load's line harmonic current. Only few readily available parameters are used in the method.
  • Journal article
    Alessandri A, Baglietto M, Parisini T, Zoppoli Ret al., 1999,

    A neural state estimator with bounded errors for nonlinear systems

    , IEEE TRANSACTIONS ON AUTOMATIC CONTROL, Vol: 44, Pages: 2028-2042, ISSN: 0018-9286
  • Journal article
    Pal BC, Coonick AH, Cory BJ, 1999,

    Robust damping of inter-area oscillations in power systems with superconducting magnetic energy storage devices

    , IEE P-GENER TRANSM D, Vol: 146, Pages: 633-639, ISSN: 1350-2360

    The decentralised design of robust damping controllers is presented based on the linear matrix inequality (LMI) approach employing several superconducting magnetic energy storage (SMES) devices. These controllers are aimed at enhancing the damping of multiple inter-area modes in a large power system. The paper describes a comprehensive and systematic way of designing these controllers. Eigenvalue technique and nonlinear simulations further verify the robustness of the damping controllers for various operating conditions and load characteristics.
  • Journal article
    Parisini T, Sacone S, 1999,

    A hybrid receding-horizon control scheme for nonlinear systems

    , SYSTEMS & CONTROL LETTERS, Vol: 38, Pages: 187-196, ISSN: 0167-6911
  • Journal article
    Laiou MC, Astolfi A, 1999,

    Discontinuous control of high-order generalized chained systems

    , SYSTEMS & CONTROL LETTERS, Vol: 37, Pages: 309-322, ISSN: 0167-6911
  • Journal article
    Shrivastava Y, Hui SY, Sathiakumar S, 1999,

    Noise analysis of dc-ac random PWM schemes

    , IEEE Transactions on Power Electronics, Vol: 14, Pages: 761-770, ISSN: 0885-8993

    Random pulsewidth modulation (RPWM) techniques for dc-ac power converters usually work well with high-sampling frequency. When RPWM schemes are implemented in digital signal processors (DSP's), the sampling frequency is limited by the speed of the processors. This paper analyzes the noise spectrum of various DSP-implemented RPWM techniques using a statistical approach. The relationship of the noise components and the sampling frequency for both the standard RPWM and the weighted RPWM methods is generalized. The dependency of the noise characteristics on various factors is calculated theoretically and verified experimentally. The generalized noise theory for randomized PWM switching provides useful practical guidelines to the choice of sampling frequency.
  • Conference paper
    Fenu G, Parisini T, 1999,

    A note on nonparametric kernel smoothing for model-free fault symptom generation

    , IFAC Workshop on On-line Fault Detection and Supervision in the Chemical Process Industries, Publisher: PERGAMON-ELSEVIER SCIENCE LTD, Pages: 1175-1179, ISSN: 0005-1098
  • Journal article
    Pytlak R, Vinter RB, 1999,

    Feasible direction algorithm for optimal control problems with state and control constraints: Implementation

    , JOURNAL OF OPTIMIZATION THEORY AND APPLICATIONS, Vol: 101, Pages: 623-649, ISSN: 0022-3239
  • Journal article
    Astolfi A, 1999,

    Exponential stabilization of a wheeled mobile robot via discontinuous control

    , JOURNAL OF DYNAMIC SYSTEMS MEASUREMENT AND CONTROL-TRANSACTIONS OF THE ASME, Vol: 121, Pages: 121-126, ISSN: 0022-0434
  • Journal article
    Hui SYR, Chung H, 1999,

    Paralleling power converters for AC-DC step-down power conversion with inherent power factor correction

    , IEE Proceedings: Electric Power Applications, Vol: 146, Pages: 247-252, ISSN: 1350-2352

    The authors describe the modular development of a single-stage AC-DC step-down power converter. The converter offers advantages such as simple DC-DC type switching control, electrically isolated output and inherent power factor correction. It also provides single-stage power conversion without using power devices with excessively high voltage and current rating, the flexibility for expansion of power capability, and a simplification of design and production procedure for the manufacturing of power converter products. The operating modes of the converter are described and analyzed. Experiments have confirmed the validity of the modular converter operation.
  • Journal article
    Angeli D, 1999,

    Input-to-state stability of PD-controlled robotic systems

    , Automatica, Vol: 35, Pages: 1285-1290, ISSN: 0005-1098

    The external stability for nonlinear systems is investigated. An important issue in systems theory is to provide suitable estimates of these state variables in terms of past inputs. A sufficient condition for input-to-state stability is presented for systems admitting a Lyapunov function with negative semi-definite derivative. An application to proportional-derivative-controlled robotic manipulators is described.
  • Journal article
    Hui SY, Chung HSH, Tang SC, 1999,

    Coreless printed circuit board (PCB) transformers for power MOSFET/IGBT gate drive circuits

    , IEEE Transactions on Power Electronics, Vol: 14, Pages: 422-430, ISSN: 0885-8993

    Gate drive circuits for modern power electronic switches, such as MOSFET and insulated gate bipolar transistor (IGBT), often require electrical isolation. This paper describes the modeling and experimental results of some coreless printed circuit board (PCB)-based transformers that can be used for MOSFET and IGBT devices at high-frequency (500 kHz to 2 MHz) operation. PCB-based transformers do not require the manual winding procedure and thus simplify the manufacturing process of transformer-isolated gate drive circuits. With no core loss, coreless transformers are found to have favorable characteristics at high-frequency operations. This project demonstrates an important point that the size of the magnetic core can approach zero and become zero when the frequency is sufficiently high.
  • Journal article
    Hui SYR, Ho YKE, Chung H, 1999,

    Modular single-stage, three-phase full-bridge converter with inherent power factor correction and isolated output

    , IEE Proceedings: Electric Power Applications, Vol: 146, Pages: 407-414, ISSN: 1350-2352

    The modular development of a three-phase, single-stage AC-DC power converter based on single-phase AC-DC full-bridge converters is described. Three-wired and four-wired modular converter systems are examined and compared. The three-wired system is found to have inherent power factor correction and is better than the four-wired system in terms of harmonic content. The fluctuation of the converter neutral voltage in the three-wired system and the voltage stress on the power switches are analysed. A simulation based on a PSPICE model is included. The modular converter does not have a minimum component count when compared with non-modular converters. But the modular converter offers attractive features such as simple DC-DC switching control, electrically isolated output, inherent power factor correction and single-stage power conversion without using power devices with excessively high voltages and current ratings. It also has flexible power expandability and the potential to simplify the design and production of high-power AC-DC power converter products. The operation of the modular full-bridge converter has been confirmed with a 1.5kW prototype. Both predictions and measurements show that the power quality of three-wired modular converter system is good and well above IEC-1000 standards.
  • Journal article
    Angeli D, Mosca E, 1999,

    Command governors for constrained nonlinear systems

    , IEEE Transactions on Automatic Control, Vol: 44, Pages: 816-820, ISSN: 0018-9286

    A method is described for set-point tracking in nonlinear systems when pointwise-in-time input and/or state inequality constraints are to be enforced. It consists of adding to a primal compensated system a nonlinear device called command governor (CG) whose action is based on the current state, set-point, and prescribed constraints. The CG selects at any time the system input via a receding-horizon strategy from a virtual sequence amongst all possible command sequences by solving a constrained quadratic optimization problem. Provided that the initial state be admissible, the overall system is proved to fulfill the constraints and have desirable performance stability properties.
  • Journal article
    Tang SC, Hui SY, Chung HSH, 1999,

    Coreless printed circuit board (PCB) transformers with multiple secondary windings for complementary gate drive circuits

    , IEEE Transactions on Power Electronics, Vol: 14, Pages: 431-437, ISSN: 0885-8993

    This paper describes the modeling and implementation of a coreless printed circuit board (PCB)-based transformer with 'multiple' secondary outputs. This new PCB transformer has been successfully applied in complementary gate drive circuits in a novel low-profile power converter with high-power density and a converter bridge. The PCB-based transformers do not require the manual winding procedure and thus simplify the manufacturing process of transformer-isolated gate drive circuits. The use of the multiple secondary outputs can in principle simplify the complementary gate drive circuits that are often required in many power electronics applications.
  • Journal article
    Hui SY, Tang SC, Chung HSH, 1999,

    Optimal operation of coreless PCB transformer-isolated gate drive circuits with wide switching frequency range

    , IEEE Transactions on Power Electronics, Vol: 14, Pages: 506-514, ISSN: 0885-8993

    Gate drive circuits for power MOSFET's and insulated gate bipolar transistors (IGBT's) often require electrical isolation. Coreless printed circuit board (PCB) transformers have been shown to have desirable characteristics from a few hundreds of hertz to a few megahertz and can be used for both power and signal transfer at low-power level. At low operating frequency, the magnetizing inductance has such low impedance that the driving power requirement could become excessive. This paper describes the use of a coreless PCB transformer for isolated gate drive circuits over a wide-frequency range. Based on a resonance concept, the optimal operating condition that minimizes the power consumption of the gate drive circuits is developed and verified with experiments. The coreless PCB transformer demonstrated here confirms a fundamental concept that the size and volume of a magnetic core could approach zero and become zero if the operating frequency is sufficiently high. Coreless PCB transformers do not require the manual winding procedure and thus simplify the manufacturing process of transformer-isolated gate drive circuits and low-power converters. Their sizes can be much smaller than those of typical core-based pulse transformers. The electrical isolation of a PCB is much higher than that of an optocoupler.
  • Journal article
    Astolfi A, 1999,

    Exponential stabilization of a wheeled mobile robot

    , ASME, Journal of Dynamic Systems Measurement and Control, Vol: 121, Pages: 121-126
  • Conference paper
    Muthu R, Green TC, Frankland JD, 1999,

    DC uninterruptable power supply topologies

    , Universities Power Engineering Conference 1999, Pages: 411-414
  • Conference paper
    Mazenc F, Astolfi A, Lozano R, 1999,

    Lyapunov Function for the Ball and Beam: Robustness Property

    , 38th Conference on Decision and Control, Phoenix, AZ
  • Conference paper
    Parisini T, Sacone S, 1999,

    A hybrid receding-horizon control scheme for nonlinear discrete-time systems

    , 5th International Hybrid Systems Workshop, Publisher: SPRINGER-VERLAG BERLIN, Pages: 262-278, ISSN: 0302-9743
  • Journal article
    Astolfi A, 1999,

    Output feedback stabilization of the angular velocity of a rigid body

    , Systems and Control Letters, Vol: 36, Pages: 181-192
  • Conference paper
    Laiou C, Astolfi A, 1999,

    Quasi smooth control of chained systems

    , American Control Conference, San Diego, CA
  • Conference paper
    Ortega R, Astolfi A, Bastin G, Rodrigues-Cortes Het al., 1999,

    Output feedback control of food-chain systems

    , International Workshop on New Directions in Nonlinear Observer Design, Publisher: SPRINGER-VERLAG, LONDON LTD, Pages: 291-310, ISSN: 0170-8643
  • Conference paper
    Green TC, Newton A, Andrew D, 1999,

    Choice of Converter Topologies and Power Distribution Topologies Within Process Plants

    , Universities Power Engineering Conference, Pages: 316-319
  • Book chapter
    Astolfi A, Menini L, 1999,

    Further results on decoupling with stability for Hamiltonian systems

    , Stability and stabilization, Editors: Aeyels, van der Schaft, Lamnabhi-Lagarrigue, Publisher: Springer Verlag
  • Conference paper
    Antonelli R, Astolfi A, 1999,

    Output feedback regulation for nonlinear chemical processes with input constraints

    , Aiche Annual Meeting, Dallas, 1999
  • Conference paper
    El-Zobaidi H, Jaimoukha IM, 1999,

    Multi-objective model and controller reduction

    , IFAC World Congress, Beijing, China, Pages: 3982-3983
  • Journal article
    Laiou C, Astolfi A, 1999,

    [no title supplied on import]

    , Systems and Control Letters, Vol: 37, Pages: 309-322

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